Septic Tank Full Or Overflowing

What's happening?

A septic tank is an underground tank where the solids sink and the liquid flows out to a drainage field. In England, GOV.UK says that if you are responsible for one you must meet the general binding rules, which include not causing pollution, getting sludge removed before it exceeds capacity, and having maintenance done by someone competent. In Wales, Natural Resources Wales explains that if solid material builds up too much it can flow into the drainage field and lead to clogging, and recommends checking the drainage field every month to make sure it is not waterlogged and the effluent is not backing up towards the tank. A tank that is full or overflowing is a pollution risk as well as a nuisance. A cesspool is different: in England, GOV.UK says the general binding rules do not apply to it, and it has to be emptied regularly.

What usually causes it?

• Sludge has built up beyond the tank's capacity because it has not been emptied often enough
• Solids have passed into the drainage field and clogged it
• A waterlogged drainage field, with effluent backing up towards the tank
• A treatment plant that has not been serviced or has a failed part
• A system that does not meet the general binding rules, or a non-standard system

Is it dangerous?

Medium. In England, GOV.UK says the sewage must not cause pollution, and if the Environment Agency finds your system may be causing pollution it will contact you and may require changes. Keep children and pets away from wet ground or sewage on the surface. Leave the tank lid closed: opening or entering a tank is a job for the emptying contractor.

Can I fix it myself?

Use less water where you can until it is emptied. Check where the tank and drainage field are, and whether the ground is waterlogged, sewage is on the surface or the outlet is not running clear. Arrange for the tank to be emptied by a registered contractor: in Wales, Natural Resources Wales suggests every 12 to 24 months for a septic tank, and in England GOV.UK says to do it at least once a year or as the manufacturer instructs. Check your maintenance records. In England, report pollution through the GOV.UK environmental incident service.

When should you call a drainage engineer?

Call an emptying contractor or septic tank engineer when drains back up, when there is sewage on the ground, when the tank has not been emptied for a year or more, or when the drainage field is waterlogged.

What will the drainage engineer actually do?

• Empty and desludge the tank and check its condition
• Inspect the outlet and the pipes to the drainage field for blockage and damage
• Check the drainage field or soakaway and advise on repair or replacement
• Service a treatment plant and check its pump and alarm
• Advise on emptying intervals and on the general binding rules for the system

Who fixes this

• Septic tank emptying
• Sewage treatment plant servicing

Questions people ask

Sources & References

1. GOV.UK (England): septic tanks and sewage treatment plants, what you need to do
2. GOV.UK (England): general binding rules, small sewage discharge to the ground
3. Natural Resources Wales (Wales): running your household sewage treatment system correctly
4. GOV.UK (England): report an environmental incident